You learn you need a medical implant—an artificial hip, for example, or a false tooth anchored in your jaw with a metal shank. Your doctor tells you that your body might reject the device, maybe within several years. Ideally, the device should stay in place indefinitely.
Aita's current work, initially supported by a National Science Foundation grant in 2000, grows out of her longtime study of the physics and chemistry of vacuum sputter deposition coatings. This process involves fabricating coatings in a low-pressure plasma reactor. She is currently investigating the use of oxide coatings as corrosion-resistant substances. Photograph by Pete Amland.
Materials Professor Carolyn Aita is studying the causes of implant rejection and how it can be minimized by better device coatings. "Rejection is caused when there is localized corrosion, when the metal ions leave the device and enter the surrounding tissue," she says. "This not only causes rejection of the device, but the ions enter the bloodstream, lymph system or remote organs, which can cause cancer."
Aita has a pending patent for "self-repairing nanostructured ceramic coatings for protection of blood-interfacing implants," which could prevent blood from clotting in an indwelling catheter and prevent infection at the site of the implant. Other potential applications include the coating surrounding an artificial heart and the ball-and-socket joint used in hip replacements.
Aita's current work, initially supported by a National Science Foundation grant in 2000, grows out of her longtime study of the physics and chemistry of vacuum sputter deposition coatings. This process involves fabricating coatings in a low-pressure plasma reactor.
This microscopic image shows a perforated pit in coated stainless steel—an example of negative reaction between an implant and surrounding tissue—a picture that Aita describes as "beautiful but bad." Images courtesy Carolyn Aita
She is currently investigating the use of oxide coatings as corrosion- resistant substances. "Sputter deposition enables us to make materials that have never been made before, such as the smart super-plastic material that has potential use for biomedical applications such as implants and indwelling catheters," she says.
Supported by a Small Grant for Exploratory Research from the National Science Foundation, Aita is currently working to demonstrate the feasibility of a novel approach to the corrosion protection of metal implants. She's developing a "smart" ceramic coating that adjusts to the human physiological environment to protect an underlying metal implant against corrosion. This coating could find use in medical applications beyond the orthopedic field.
Another bad interaction between tissue and an implant: brittle fracture and holes decorating polishing scratches in stainless steel coated with an alumina film.
"Our goal is for these coatings to be used in any medical device where there needs to be synergy between the mechanical and chemical properties of the device," Aita says.
"It's fun to do something new in my field, and it's also nice to be doing something useful," she adds. "I'm proud of this work."
Aita is currently the person-in-charge at the Advanced Coatings Experimental Laboratory, known as AceLab, an independently funded laboratory with three full-time staff and two graduate students. Two significant components of this lab are "Dorothy," the sputter deposition reactor located in a "clean room" in the basement of the Engineering and Mathematical Sciences building, and "Esther," the vacuum chamber on the 11th floor of the building. "They're 'big toys,' " says Elizabeth Hoppe, associate researcher in the AceLab who runs the experiments on Dorothy. The reactors are named after two pioneering women in vacuum science, Dorothy Hoffman and Esther Krikorian.
Aita's interest in science developed, surprisingly, after college. Shortly after receiving a bachelor's in fine arts and art history from Brooklyn College of the City University of New York in 1966, she married and settled in to be a homemaker. "It never occurred to me I would have a career," she says. But marriage to Michael, a physicist, and her own intellect and curiosity soon led her to the study of architecture ("I wanted to know how buildings stand up," she recalls), then to physics. "I loved it, and it came easily to me," she says. "I thought I'd never have to memorize information again—I could solve problems using equations, not words!"
Aita earned a bachelor's in physics at Utica College of Syracuse University in 1970, a master's in physics at Queens College of the City University of New York in 1974, and a doctorate in materials science from Northwestern University in 1977. After four years of working in industry in northern Illinois, she joined the UWM faculty in 1981 as an assistant professor.
"I wanted to have students," she says. "Teaching forces you to form ideas clearly in your own mind in order to communicate them to someone else." Promoted to associate professor in 1984, Aita was named professor in the Materials Department and joined the Laboratory for Surface Studies in 1988. She earned a professorship in the Department of Electrical Engineering and Computer Science in 1994.
In 1988, Aita became a Wisconsin Distinguished Professor of Materials Engineering, the first Distinguished Professor of Engineering at UWM and one of two women with that distinction in the UW System. The distinguished professorship funds about 20 faculty members System-wide who must actively seek financial support from the Wisconsin business community each year to match the state's contribution to their work.
The distinguished professorship of engineering requires its recipients to collaborate with industrial partners, and Aita has worked to build bridges between academia and the business community. One partner is Badger Meter, a Milwaukee company that manufactures fluid measurement equipment. Many fluids, including household water, can be very corrosive, and beginning in 1999, Badger Meter became interested in finding out how Aita's work could be helpful to them. "We were impressed with the work being done on corrosion at the AceLab," says Dennis Webb, vice president of engineering at Badger Meter.
Elizabeth Hoppe, associate researcher in the AceLab, demonstrates "Dorothy," the sputter deposition reactor located in a "clean room" in the basement of the EMS building. Dorothy and "Esther," the vacuum chamber on the 11th floor, are named after two pioneering women in vacuum science, Dorothy Hoffman and Esther Krikorian. Photograph by Pete Amland.
"Sometimes it's difficult for people in the academic community to relate to those of us in the manufacturing environment because we have the pressing issue of making money," Webb says. "Carolyn is interested in our issues, and she understands them."
Fortunately for UWM students, Aita also finds time to be an educator and mentor as well as a scientist, having taught a variety of graduate and undergraduate courses and supervised more than 20 master's theses and a dozen Ph.D. dissertations. "She is very supportive of her students, especially women students," says AceLab associate researcher Hoppe, who is also pursuing her doctorate. "At meetings, she makes sure we get recognition for our work, and she helps us network in the scientific community."
Aita says teaching refreshes her. "The best thing about students is that they ask questions, and I encourage them to keep doing it until I can't answer them," she says. "Each answer leads to the next question, it's like unraveling a puzzle. I'm never bored."
